1. Field of the Invention
This invention relates to photographic film cassettes.
2. Description of the Prior Art
Convenience, simplicity, reliability and cost are always prime considerations for potential purchasers and users of consumer products. In terms of photographic systems for amateur use, convenience may be related to the size and weight of the system; simplicity to the number of steps required of the user in the order to produce a finished photograph; reliability to the consistent performance of the system under a variety of operating conditions; and cost to the effectiveness of the system when compared to the previous three considerations. The goal for a highly cost-effective system, therefore, is to maximize convenience, simplicity and reliability while minimizing cost.
Fully automatic photographic systems that are compact, lightweight and capable of producing low-cost, finished, waste-free prints immediately after a picture is "snapped" surely meet these requirements. Such systems, however, purposely invite complexity and technical sophistication in order to satisfy these criteria. For example, a system of the self-developing type where the user effort represents the nominal steps of simply focusing and pressing an exposure-initiating button, while the system assumes the major responsibility for automatically exposing and processing the exposed self-developing film unit whereby it becomes a finished print outside of the camera, certainly represents simplicity from the user point of view. It is evident, though, that simplifying the user's task necessarily increases the system complexity because the system now has to assume the burden of those tasks normally performed by the user, and increased complexity generally implies higher system cost.
The goal of high cost-effectiveness then represents a choice to some degree between somewhat mutually inconsistent requirements. An optimized system can be achieved only by selecting the best compromise consistent with particular performance levels and design constraints imposed on the specific system.
A great many photographic systems have been developed which approach the goal of cost-effectiveness in a variety of ways. If we define the system as comprising a camera and film whose performance satisfies the consumer requirements as outlined above, we find disclosed in the patent literature what represents one of these approaches. U.S. Pat. No. 3,714,879 entitled, "Reflex Camera", issued to Edwin H. Land, et al. on Feb. 6, 1973, shows and describes a fully automatic, single-lens, reflex camera capable of being folded into a thin, compact shape suitable for convenient carrying in the pocket of a garment. This camera is intended to be used with a disposable film cassette including an integrated power supply. Such cassettes are described in considerable detail in, for example, U.S. Pat. Nos. 3,543,662 issued Dec. 1, 1970; 3,651,746, issued Mar. 28, 1972; 3,779,770, issued Dec. 18, 1973; 3,682,062, issued Aug. 8, 1972; 3,631,776, issued Jan. 4, 1972; and 3,705,542, issued Dec. 12, 1972. These patents describe photographic film assemblages, each of which basically comprises a cassette and a plurality of film units, preferably of the self-developing type, arranged in stacked relation and adapted to be exposed and then withdrawn from the cassette and processed. Also included as an integral part of the cassette is a battery or power supply for operating the components of the camera in which the film units are exposed and processed. The function of the battery is to supply the electrical power requirements to various camera subsystems whose functions correspond closely to those steps in the photographic process that would normally be performed by the system user. Such subsystems include, for example, the exposure control system, film-transport system, and a motor-powered mechanism for processing the exposed film unit. One of the foregoing U.S. Pat. Nos. 3,631,776, shows, in addition, an arrangement for connecting a thermistor in an exposure control system for purposes of changing exposure times to compensate for changes in film speed due to temperature variations. The battery additionally supplies power to logic circuits within the camera that function to control its sequential operation. In the case where the user is taking a flash picture, the battery additionally supplies the power necessary to ignite the flash bulb or could be used, alternatively, to charge a strobe unit used for artificial lighting. Batteries incorporated in such film assemblages therefore need to have a power-delivery capacity sufficient to meet the power requirements of the camera under the worst foreseeable conditions.
This would occur in the case where all pictures taken were flash pictures. Under this condition, as with others, the power would also have to be sufficient to supply the energy necessary to assure that the film would be transported through the processing system at some minimum speed which would insure proper coverage of the exposed film unit by a processing fluid contained within the film unit itself. In order to assure that these power drain requirements are fully met, these batteries have been designed to have an excess power-delivery potential even under the worst case conditions. Because of the integral nature of the cassette design incorporating both the film units and the battery within it, the cassette, once all of the film units have been used, would normally be discarded. This means that the excess of residual electrical power left in the battery would be irretrievably wasted unless some convenient means were provided in the design of the cassette which would allow the user to easily remove the battery so that its residual energy could be utilized.
Although the residual power of these batteries will depend on a variety of conditions, it is not unreasonable, based on recent experience, to expect that the battery may be recycled for use with a number of film cassettes. Since the battery represents a major portion of the cost of the film assemblage as it presently exists, it is obvious that the cost-effectiveness of a system could be dramatically improved and thereby made more attractive to the potential consumer as a result of the per-unit cost reduction that may be realized by distributing the cost of a battery over a number of film cassettes. These would be less expensive to purchase if sold individually, without a battery, but with provision for easily inserting or removing one.
In addition, such an assemblage could be purchased and used with a camera system not requiring the battery for its operation. Such a camera might be similar to the one shown and described in U.S. Pat. No. 3,757,657 entitled, "Manually Operable Film-Advancing Apparatus", issued to Vaito K. Eloranta, et al. on Sept. 11, 1973. The flexibility of having a single film cassette which may be universally used with either a manually operable or electrically powered camera system therefore seems most desirable from a cost viewpoint.
There are other advantages related to reliability and production costs. First, the reliability aspect will be considered. It will be recalled that reliability was defined as the consistent performance of the system under a variety of conditions. One condition under which a catastrophic system failure could occur would be when there was a disparity between the lives of the film and the battery. If the expected life of either the battery or the film expired, the result would be the same. In either case, the film assemblage as a whole would be useless. The present invention would prevent such a situation because the purchaser could always be assured, by comparing the expiration dates of the film and battery, that he would always be using a fresh battery with usable film. Also, the film assemblage manufacturer's inventory and production-control problems associated with matching battery and film units having the same life could be virtually eliminated, thereby reducing his costs. The cost savings could be passed on to the consumer.
Another area where costs could potentially be reduced by utilizing the present invention is related to the assemblage manufacturer's product yield. Suppose the manufacturer decided to sell both versions of the invention, both with and without the battery. In the former case, if he discovered a battery failure in the assemblage, it would be an easy task for him to simply replace the battery. Unlike the present assemblages which integrate the battery and film in a single unit, he would have to replace only the battery and would therefore not lose the film, as is presently the case. Therefore, his yield could be substantially increased while his costs proportionately reduced.
A reissued U.S. Pat., Re. No. 26,181, discloses a film spool adapted to house a battery that may be iserted into or removed from its hollowed out inner cylindrical core without exposing film that is rolled in the exterior of the core and surrounded by a cylindrical dark chamber. The present invention is structurally distinct from this, however, in that it deals with a housing arangement that incorporates both a plurality of flat film units and a flat battery in substantially parallel alignment within a single chamber that is partitioned into two separate compartments, one light sealed from the other.
U.S. Pat. No. 3,587,425 discloses a flat battery securely attached to the exterior of the flat housing having an interior chamber in which there is disposed a plurality of flat film units aligned substantially parallel to the battery. The present invention differs from this in that the battery can be easily inserted into or removed from the confines of the film chamber without exposing the film units therein.
In summary, it is believed that the present invention provides the art with an improved photographic film assemblage because it permits a user to easily insert or remove a flat battery from the assemblage so that its residual power may be reused in another similar assemblage.